As is already possible for quizzes with non-relative dates, a teacher should be able to override the quiz open date in a relative dates course for a student.
- The override should not affect any other students
- If a student's quiz open date is overridden, the student should only be able to attempt the quiz on or after the override date.
- The override form should show the relative quiz open date for that user
- The 'Revert to quiz defaults' button should reset the open date to the current student's relative quiz open date.